Helical coil inserts are commonly installed into tapped holes of a workpiece so that threaded fasteners such as screws can be held more securely. These inserts are frequently used to improve the gripping of threaded fasteners made of relatively hard materials, such as various steel alloys, when installed in relatively soft parent materials, such as aluminum. Helical coil inserts typically include a diametrical tang used as a grip by a mandrel of the installation tool for screwing the helical coil insert into the tapped hole.
Helical coil inserts of this kind are usually installed by pre-winding them to reduce their diameter, and then rotatably threading them into a tapped hole. Once installed, the inserts expand from their contracted diameters and press radially outwardly against the walls defining the tapped holes, whereby the insert is securely held in place. Power tools for installing inserts are typically driven by an air motor and include a tubular body having a threaded bore extending along its axis and an opening at one end of the body for placing an insert in the bore. A mandrel is rotated by the motor within the threaded bore into engagement with the insert. Advancement of the mandrel forces the insert through a pre-winder, which reduces the insert's diameter, and from there into a tapped hole in an adjacent workpiece.
Once the insert is installed at the correct depth in the bore of the workpiece, the mandrel is reversed until it is removed from the insert. In many instances, particularly if a through-going hole is lined with an insert, the tang must be removed after installation as otherwise it would interfere with a bolt engaging the insert. To facilitate removal of the tang, a notch is conventionally provided in the wire near the point where the diametrical tang joins the adjacent coil convolution. Thus, after using a conventional power tool to install the insert, the installer uses a second tool to break the tang at the notch.
This two-tool process is time consuming and inefficient, particularly when many bores must be lined with helical coil inserts, such as in a manufacturing setting. Great efficiencies and cost savings would be realized by combining and simplifying the helical coil insert installation and tang removal process.